Heteroaryl amines as novel acetyl cholinesterase inhibitors

ABSTRACT

Compounds of the formula ##STR1## wherein ring A, ring B, ring D, R 2 , R 3 , R 4 , R 5 , R 6 ,R 11 , R 12 , R 13 , E, G, X and P are as defined below. The compounds of formula I are cholinesterase inhibitors and are useful in enhancing memory in patients suffering from dementia and Alzheimer&#39;s disease.

This is a divisional application of application Ser. No. 08/211,044,filed on Mar. 9, 1994 now U.S. Pat. No. 5,574,046, which is the UnitedStates national phase of PCT/US92/07230, which was filed on Aug. 31,1992, which is a continuation of Ser. No. 07/771,283 filed Oct. 3, 1991now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to heteroaryl amines of the formula Ibelow, and pharmaceutically acceptable salts of such compounds. Thecompounds of formula I are acetylcholinesterase inhibitors and areuseful in enhancing memory in patients suffering from dementia andAlzheimer's disease.

Alzheimer's disease is associated with degeneration of cholinergicneurons in the basal forebrain that play a fundamental role in cognitivefunctions, including memory. Becker et al., Drug Development Research,12, 163-195 (1988). As a result of such degeneration, patients sufferingfrom the disease exhibit a marked reduction in acetylcholine synthesis,choline acetyltransferase activity, acetylcholinesterase activity andcholine uptake.

It is known that acetylcholinesterase inhibitors are effective inenhancing cholinergic activity and useful in improving the memory ofAlzheimer's patients. By inhibiting acetylcholinesterase enzyme, thesecompounds increase the level of the neurotransmitter acetylcholine, inthe brain and thus enhance memory. Becker et al., supra, report thatbehavioral changes following cholinesterase inhibition appear tocoincide with predicted peak levels of acetylcholine in the brain. Theyalso discuss the efficacy of the three known acetylcholinesteraseinhibitors physostigmine, metrifonate, and tetrahydroaminoacridine.

U.S. patent application Ser. No. 07/639,614, filed Jan. 10, 1991, andU.S. patent application Ser. No. 07/676,918, filed Mar. 28, 1991, bothof which are assigned in common with the present application, also referto heteroaryl amine acetylcholinesterase inhibitors.

SUMMARY OF THE INVENTION

The present invention relates to compounds of the formula ##STR2##wherein one of R², R³ and the side chain containing ##STR3## mayoptionally be attached to the carbon atom designated by an asterisk inring B rather than to a member of ring A;

ring A is benzo, thieno, pyrido, pyrazino, pyrimido, furano, seleno,pyrrolo, thiazolo, or imidazolo;

R¹ is phenyl, phenyl-(C₁ -C₆)alkyl, cinnamyl or heteroarylmethyl,wherein the heteroaryl moiety of said heteroarylmethyl is selected fromimidazolo, thiazolo, thieno, pyrido and isoxazolo, and wherein saidphenyl and said heteroaryl moiety may optionally be substituted with oneor two substituents independently selected from (C₁ -C₆)alkyl, (C₁-C₆)alkoxy and halo;

R² and R³ are independently selected from hydrogen, (C₁ -C₆)alkoxy, (C₁-C₆)alkyl optionally substituted with from one to three fluorine atoms,benzyloxy, hydroxy, phenyl, benzyl, halo, nitro, cyano, COOR⁴, CONHR⁴,NR⁴ R⁵, NR⁴ COR⁵, or SO_(p) CH₂ -phenyl wherein p is 0, 1 or 2;

or R² and R³ are attached to adjacent carbon atoms and form, togetherwith the carbons to which they are attached, a five or six membered ringwherein each atom of the ring is carbon, nitrogen or oxygen (e.g., amethylenedioxy, ethylenedioxy or lactam ring);

R⁴ and R⁵ are independently selected from hydrogen and (C₁ -C₆)alkyl, orR⁴ and R⁵, when part of said NR⁴ R⁵, optionally form, together with thenitrogen to which they are attached, a ring containing four to eightmembers wherein one atom of the ring is nitrogen and the others arecarbon, oxygen or nitrogen, or R⁴ and R⁵, when part of said NR⁴ COR⁵,optionally form, together with the nitrogen and carbon to which they areattached, a four to eight membered lactam ring;

X is nitrogen or CH;

Y is oxygen, sulfur or ##STR4## R⁶ is hydrogen, (C₁ -C₆)alkyl, CO(C₁-C₆)alkyl or SO₂ --, phenyl, wherein the phenyl moiety of said SO₂-phenyl may optionally be substituted with from one to five substituentsindependently selected from (C₁ -C₄) alkyl;

n is an integer from 1 to 4;

each q is independently 1 or 2; and

Z is oxygen or sulfur;

with the proviso that any CH_(q) group wherein q is 1 must be attachedto one and only one other CH_(q) group wherein q is 1.

The present invention also relates to the pharmaceutically acceptableacid addition salts of compounds of the formula I. Examples of suchpharmaceutically acceptable acid addition salts are the salts ofhydrochloric acid, p-toluenesulfonic acid, fumaric acid, maleic acid,citric acid, succinic acid, salicylic acid, oxalic acid, hydrobromicacid, phosphoric acid, methanesulfonic acid, tartaric acid, di-p-toluoyltartaric acid, and mandelic acid.

This invention further relates to a pharmaceutically composition forinhibiting acetylcholinesterase comprising a compound of the formula Ior a pharmaceutically acceptable acid addition salt thereof, and apharmaceutically acceptable carrier.

The invention further relates to a method for inhibitingacetylcholinesterase in a mammal comprising administering to a mammal anamount of a compound of the formula I or a pharmaceutically acceptableacid addition salt thereof effective in inhibiting acetylcholinesterase.

The invention further relates to a method for enhancing memory ortreating or preventing Alzheimer's disease in a mammal comprisingadministering to a mammal an amount of a compound of the formula I or apharmaceutically acceptable acid addition or salt thereof effective inenhancing memory or treating or preventing Alzheimer's disease.

The term "mammal", as used herein, includes humans.

The term "halo", as used herein, includes chloro, bromo or fluoro.

Preferred compounds of this invention are compounds of the formula##STR5## wherein X is CH, CCH₃, CCH₂ CH₃ or N; Y is NH, NCH₃, NCH₂ CH₃,S, O or NSO₂ C₆ H₅ ; R² and R³ are independently selected from the groupconsisting of

(C₁ -C₄)alkyl, chloro, fluoro, methoxy, amino and ##STR6## or R² and R³,together with the carbons to which they are attached, form a γ-lactamring; and R¹ is benzyl, methoxybenzyl, fluorobenzyl or a group of theformula ##STR7## wherein W is hydrogen, (C₁ -C₆)alkyl, phenyl or benzyl.

Specific preferred compounds of the invention are:

1-(2-methyl-1H-benzimidazol-5-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(2-phenyl-1H-benzimidazol-5-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(1-ethyl-2-methyl-1H-benzimidazol-5-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(2-methyl-6-benzothiazolyl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(2-methyl-6-benzothiazolyl)-3-[1-[(2-methyl-4-thiazolyl)methyl]-4-piperidinyl]-1-propanone;

1-(5-methyl-benzo[b]thien-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(6-methyl-benzo[b]thien-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(3,5-dimethyl-benzo[b]thien-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(benzo[b]thien-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(benzofuran-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(1-phenylsulfonyl-6-methyl-indol-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(6-methyl-indol-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(1-phenylsulfonyl-5-amino-indol-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(5-amino-indol-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;and

1-(5-acetylamino-indol-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone.

Examples of other compounds of the invention are:

1-(6-quinolyl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(5-indolyl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(5-benzthienyl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(6-quinazolyl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(6-benzoxazolyl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(5-benzofuranyl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(5-methyl-benzimidazol-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(6-methyl-benzimidazol-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(5-chloro-benzo[b]thien-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(5-azaindol-2-yl)-3-(1-(phenylmethyl)-4-piperidinyl)-1-propanone;

1-(6-azabenzo[b]thien-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(1H-2-oxo-pyrrolo[2',3',5,6]benzo[b]thieno-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(6-methyl-benzothiazol-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(6-methoxy-indol-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(6-methoxy-benzo[b]thien-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;

1-(6-acetylamino-benzo[b]thien-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone;and

1-(5-acetylamino-benzo[b]thien-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone.

Formula I above includes compounds identical to those depicted but forthe fact that one or more hydrogen, nitrogen or carbon atoms arereplaced by isotopes thereof (e.g., tritium, carbon-14 or nitrogen-15isotopes). Such compounds are useful as research and diagnostic tools inmetabolism pharmacokinetic studies and in binding assays.

The compounds of formula I may have optical centers and may thereforeoccur in different isomeric forms. The invention includes all isomers ofsuch compounds having formula I, including mixtures thereof.

DETAILED DESCRIPTION OF THE INVENTION

The preparation of compounds having the formula I is illustrated in thefollowing reaction schemes. Except where otherwise stated, in thereaction schemes and discussion that follow, R¹, R², R³, R⁴, R⁵, R⁶, n,q, p, X, Y and Z and structural formula I are defined as above.

The symbol * (i.e., the asterisk) that appears in several of thestructures in the reaction schemes represents, for each structure inwhich it appears, that the side chain containing the ##STR8## group mayoptionally be attached to the carbon atom designated by the asteriskrather than to a member of ring A.

All articles, books, patents and patent applications cited in thefollowing discussion are incorporated herein by reference. ##STR9##

Scheme 1 illustrates a method of preparing compounds of the formula Iwherein Z is oxygen and the side chain containing ##STR10## is attachedto the carbon atom designated by an asterisk in ring B (hereinafterreferred to as compounds of the formula I-A).

The starting materials having the formulae II and III are eithercommercially available or obtainable by synthetic procedures reported inthe literature. (See J. Med. Chem., 33, 2777 (1990); TetrahedronLetters, 30, 6117 (1989); Eur. J. Med. Chem., 25, 191 (1990);Heterocycles, 29, 849 (1989); J. Org. Chem., 47, 757 (1982); J. Org.Chem., 54, 4350 (1989); Tetrahedron, 44, 3195 (1988); Zur. J. Med. Chem.& Chim. Ther., 21, 223 (1986); Chem. Ber., 88, 34 (1954); Tetrahedron,28, 2553 (1972); J. Chem. Soc. (C), 1733 (1968); U.S. Pat. No.4,902,694; J. Heterocyclic Chem., 25, 1271 (1988); Bull. Chem. Soc.Jpn., 58, 785 (1986); J.Ind. Chem. Soc., 12, 561 (1975); and SyntheticCommunications, 14, 947 (1984).

Referring to scheme 1, a compound of the formula II is reacted with theappropriate compound of formula III in the presence of a base to formthe corresponding compound of the formula IV. This reaction is usuallyperformed in an appropriate reaction inert solvent at a temperature fromabout -78° C. to about room temperature, preferably from about -78° C.to about 0° C. Suitable solvents include tetrahydrofuran (THF), ether,toluene, methylene chloride, benzene and dioxane. Suitable bases includelithium bis(trimethylsilyl)amide, lithium diisopropylamide, sodiumdiisopropylamide, sodium bis(trimethylsilyl)amide, n-butyllithium(n-BuLi), s-butyllithium (s-BuLi) and t-butyllithium (t-BuLi).

The compound of formula IV formed in the foregoing step is thenconverted into the corresponding compound of formula I-A by reacting itwith an oxidizing agent. Examples of oxidizing agents that may be usedare manganese dioxide, chromium trioxide and selenium dioxide. Manganesedioxide is preferred. Generally, the oxidation is conducted in areaction inert solvent at a temperature from about room temperature toabout 80° C., preferably from about 50° C. to about 80° C. Examples ofsuitable solvents are methylene chloride, chloroform, ethyl acetate,benzene and toluene. Preferably, the solvent is methylene chloride orbenzene.

Scheme 2 illustrates a method of preparing compounds of the formula Iwherein Z is oxygen and n is 2, 3 or 4 (hereinafter referred to ascompounds of the formula I-A') and compounds of the formula I wherein nis 2, 3 or 4 and the (CH_(q))_(n) group contains at least onecarbon--carbon double bond (hereinafter referred to as compounds of theformula I-B). Referring to scheme 2, the starting materials having theformulae V and VI can be obtained commercially or prepared as describedin the literature. (See J. Org. Chem., 54, 4350 (1989); Tetrahedron, 44,3195 (1988); Chem. Pharm. Bull., 39, 181 (1991); Chem. Ber., 119, 2069(1986); and J. Ind. Chem. Soc., 12, 561 (1975).

As shown in scheme 2, a compound of the formula V is reacted with analdehyde of the formula VI in the presence of a base to form thecorresponding compound of formula VII. Suitable bases for this reactioninclude sodium hydride, lithium bis (trimethylsilyl) amide, piperidine,pyrrolidine, lithium diisopropylamide, sodium diisopropylamide,n-butyllithium and s-butyllithium. The reaction is usually carried outin a reaction inert solvent such as THF, dimethylformamide (DMF),dioxane, toluene, methylene chloride or ether, with THF, ether ortoluene being preferred. The reaction temperature may range from about-78° C. to about 40° C. and is preferably about -78° C. to about 0° C.

If the reaction between compounds of the formulae V and VI is conductedin the presence of a sodium or potassium (C₁ -C₅)alkoxide, it ispreferable to use toluene, DMF, THF or methylene chloride as thesolvent, with or without a (C₁ -C₄) alcohol, and to conduct the reactionat a temperature from about -40° C. and 80° C., more preferably fromabout 0° C. to about room temperature.

Subjecting the compound of formula VII so formed to an eliminationreaction yields the corresponding compound of formula I-B. Theelimination is typically carried out by reacting the compound of formulaVII, in the presence of a base, with a reagent capable of forming aleaving group upon reaction with the hydroxy group of formula VII.Appropriate reagents include acetic anhydride, R⁷ SO₂ Cl, R⁷ COCl, R⁷OCOCl and R⁷ NCO, wherein R⁷ is selected from (C₁ -C₄) alkyl or phenyloptionally substituted with (C₁ -C₆) alkyl, (C₁ -C₄) alkoxy or nitro.Examples of suitable bases are triethylamine, diisopropylethylamine,diazabicycloundecane (DBU) and diazabicyclononanone. The solvent can beany reaction inert solvent (e.g., methylene chloride, chloroform, THF ortoluene). The reaction temperature can range from about 0° C. to about60° C., and is preferably about 0° C. to about room temperature.

Alternatively, compounds of the formula I-B may be prepared by reactingthe appropriate compound of formula VII with the Burgess Inner salt. TheBurgess Inner salt may be prepared from chlorosulfonyl isocyanate,methanol and triethylamine, as described in J. Amer. Chem. Soc., 90,4744 (1968). Generally, this reaction is carried out in an inert solventsuch as THF, ether, benzene, toluene or dioxane, preferably THF, at atemperature from about room temperature to about the reflux temperatureof the solvent, preferably from about 50° C. to about 80° C.

The corresponding compound of the formula I-A' is then prepared byhydrogenation of the compound of formula I-B formed in the above step.Generally, the hydrogenation is accomplished using platinum dioxide orpalladium on carbon at a pressure of about 30 psi to about 50 psi.Suitable reaction inert solvents include THF, methanol, ethanol, ethylacetate and mixtures thereof. Preferably, the solvent is a mixture ofethanol and THF or a mixture of ethanol and ethyl acetate. The reactiontemperature may range from about 0° C. to about 60° C. The preferredtemperature is about room temperature.

The preparation of compounds having the formulae I-C and I-D areillustrated in scheme 3. Compounds of the formula I-C are thosecompounds of the formula I wherein ring A is benzo, Y is ##STR11## R⁶ ishydrogen, X is nitrogen, R³ is hydrogen and R² is attached to the carbonatom designated with an asterisk (*) in ring B. Compounds of the formulaI-D are those compounds of the formula I wherein ring A is benzo, Y is##STR12## R⁶ is other than hydrogen, X is nitrogen, R³ is hydrogen andR² is attached to the carbon atom designated with an asterisk (*) inring B.

Referring to scheme 3, the reaction of a compound of the formula IX withan aldehyde of the formula X to produce a compound of the formula XI iscarried out using the procedure depicted in scheme 2 and described abovefor reaction steps V→VII→I-B→I-A'.

The resulting compound of formula XII is then cyclized in the presenceof an acid to afford the corresponding compound of the formula I-C.Examples of acids that may be used are acetic acid, a mixture of aceticacid and a (C₁ -C₄)-alcohol, hydrochloric acid and ether saturated withhydrogen chloride. This reaction is generally conducted at a temperaturefrom about room temperature to about 120° C. Temperatures from about 60°C. to about 90° C. are preferred.

An R⁶ group may be added to the compound of formula I-C to obtain thecorresponding compound having the formula I-D by reacting theappropriate compound of formula I-C with a compound of the formula R⁶ L,wherein L is a leaving group. This reaction is typically carried out inan inert solvent in the presence of a base at a temperature from about-78° C. to about the ref lux temperature of the solvent. Suitable basesinclude sodium hydride, lithium diisopropylamide, t-butyllithium andpotassium t-butoxide. Suitable solvents include THF, methylene chloride,benzene, ether, toluene or dioxane. The reaction is preferably conductedin THF in the presence of sodium hydride at a temperature from about 0°C. to about 30° C.

Scheme 4 illustrates the preparation of compounds of the formula Iwherein Z is sulfur (hereinafter referred to as compounds of the formulaI-F) from compounds of the formula I-E. This transformation isaccomplished by reacting the compound of formula I-E with Lawesson'sReagent(2,4-bis(4-methoxyphenyl)-1,3-dithia-2,4-diphosphetane-2,4-disulfide) orphosphorus pentasulfide (P₂ S₅). Typically, this reaction is conductedin a reaction inert solvent such as THF, acetonitrile, chloroform ortoluene at a temperature from about room temperature to about 110° C. Itis preferably conducted in THF or toluene at a temperature from about60° C. to about 80° C.

Compounds of the formula I wherein R¹ is other than benzyl may beprepared from the corresponding compounds of the formula I wherein R¹ isbenzyl (hereinafter referred to as compounds of the formula I-G) asdescribed below and illustrated in scheme 5.

First, a compound of the formula I-G is reacted with a chloroformate ofthe formula ##STR13## wherein R⁹ is --ClCHCH₃, --CH₂ CH₃ or --CH₂ C₆ H₅.The preferred reactant is 1-chloroethyl chloroformate. This reaction,which affords the corresponding compound of the formula XIV, isgenerally carried out in a reaction inert solvent such as methylenechloride, chloroform, dichloroethane, THF or toluene, preferablytoluene, at a temperature from about 60° C. to about 100° C., preferablyfrom about 80° C. to about 85° C.

Heating the compound of formula XIV so formed in a (C₁ -C₄) alcohol,preferably methanol or ethanol, yields the corresponding compound of theformula XV. The reaction temperature may range from about 80° C. toabout the reflux temperature of the solvent and is preferably about thereflux temperature of the solvent.

The compound of the formula XV formed in the foregoing step is thenalkylated and thus converted into the corresponding compound of formulaI by reacting it with a compound of the formula R¹ L, wherein L is aleaving group, in the presence of a base. Examples of suitable leavinggroups are chloro, bromo, iodo, mesylate, tosylate and triflate (OTf).Suitable bases include pyridine, triethylamine, dimethylaminopyridineand potassium carbonate. Triethylamine is preferred. Generally, thealkylation is carried out in a reaction inert solvent such as methylenechloride or DMF, at a temperature from about 0° C. to about 100° C.,preferably from about room temperature to about 60° C.

In each of the above reactions, pressure is not critical. Pressures inthe range of about 0.5 atm to 3 atm are suitable, and ambient pressure(generally, about one atmosphere) is preferred as a matter ofconvenience. Also, for those reactions where the preferred temperaturevaries with the particular compounds reacted, no preferred temperatureis stated. For such reactions, preferred temperatures for particularreactants may be determined by monitoring the reaction using thin layerchromatography.

The compounds of the invention may be administered to a patient byvarious methods, for example, orally as capsules or tablets, parentallyas a sterile solution or suspension, and in some cases, intravenously inthe form of a solution. The free base compounds of the invention may beformulated and administered in the form of their pharmaceuticallyacceptable acid addition salts.

The daily dose of the compounds of the invention is generally in therange of from about 1 to 300 mg/day for the average adult human, and maybe administered in single or divided doses.

When incorporated for parenteral administration into a solution orsuspension, the compounds of the invention are present in aconcentration of at least 1 weight percent, and preferably between about4-70 weight percent (based on the total weight of the unit). Theparenteral dosage unit typically contains between about 5 to 100 mg ofactive compound(s).

Compounds of the present invention may be administered orally with aninert diluent or an edible carrier, or they may be enclosed in gelatincapsules or compressed into tablets. Such preparations should contain atleast 0.5% of active compound(s), but the concentration may varydepending upon the particular form and may be from 4 to 70 weightpercent (based on the total weight of the unit). The oral dosage unittypically contains between 1.0 mg to 300 mg of active compound.

The activity of the compounds of the present invention asacetylcholinesterase inhibitors may be determined by a number ofstandard biological or pharmacological tests. One such procedure fordetermining cholinesterase inhibition is described by Ellman et al. in"A New and Rapid Colorimetric Determination of AcetylcholinesteraseActivity", Biochem. Pharm. 1, 88, (1961).

The present invention is illustrated by the following examples. It willbe understood, however, that the invention is not limited to thespecific details of these examples. Melting points are uncorrected.Proton nuclear magnetic resonance spectra (¹ H NMR) and C¹³ nuclearmagnetic resonance spectra (C¹³ NMR) were measured for solutions indeuterochloroform (CDCl₃) and peak positions are expressed in parts permillion (ppm) downfield from tetramethylsilane (TMS). The peak shapesare denoted as follows: s, singlet; d, doublet; t, triplet; q, quartet;m, multiplet; b, broad.

EXAMPLE 11-[2-(5-Methyl-benzothienyl)]-3-[1-(phenylmethyl]-4-piperidinyl[-2-propen-1-ol

A solution of 5-methyl-benzothiophene (356 mg, 2.4 mmol) in 10 ml of drytetrahydrofuran (THF) was treated with n-butyllithium (n-BuLi) at -10°C. and the mixture was stirred at room temperature for 30 minutes. Asolution of 3-[4-(N-benzylpiperidinyl)]propenal (550 mg, 2.4 mmol) in 5ml of dry tetrahydrofuran (THF) was added to the reaction mixture atroom temperature. After stirring for 30 minutes, the mixture wasquenched with water and extracted with chloroform. The organic layer wasdried and concentrated to give 750 mg (90%) of desired product.

¹ H NMR (CDCl₃) δ 1.3-2.1 (m, 7H), 2.3-2.5 (m, 3H), 2.7-3.0 (m, 2H),3.47 (s, 2H), 5.37 (d, 1H), 5.6-5.8 (m, 2H), 7.0-7.7 (m, 9H) ppm.

The title compounds of Examples 2-4 were prepared by a method analogousto that described in Example 1.

EXAMPLE 21-[2-(6-Methyl-benzothienyl)]-3-[1-(phenylmethyl)-4-piperidinyl]-2-propen-1-ol

¹ H NMR (CDCl₃) δ 1.3-2.0 (m, 7H), 2.4 (s, 3H), 2.8-2.95 (m, 2H), 3.45(s, 2H), 5.35 (d, 1H), 5.6-5.8 (m, 2H), 7.0-7.6 (m, 9H) ppm.

EXAMPLE 31-[2-(2,5-Dimethyl-benzothienyl)]-3-[1-(phenylmethyl)-4-piperidinyl]-2-propen-1-ol

¹ H NMR (CDCl₃) δ 1.35-2.0 (m, 7H), 2.3 (s, 3H), 2.5 (s, 3H), 2.8-2.9(m, 2H), 3.5 (s, 2H), 3.7-3.8 (m, 1H), 5.5-5.9 (m, 3H), 7.0-7.8 (m, 8H)ppm.

EXAMPLE 41-(2-Benzothienyl)-3-[1-(phenylmethyl)-4-piperidinyl]-2-propen-1-ol

¹ H NMR (CDCl₃) δ 1.3-2.0 (m, 7H), 2.7-2.9 (m, 2H), 3.45 (s, 2H), 5.4(d, 1H), 5.6-5.8 (m, 2H), 7.1 (s, 1H) 7.2-7.3 (m, 7H), 7.65 (dd, 1H),7.72 (dd, 1H) ppm.

EXAMPLE 55-Methyl-benzothien-2-yl-2-[1-(phenylmethyl)-4-piperidinyl]vinyl ketone

A solution of crude1-[2-(5-methyl-benzothienyl)]-3-[1-(phenylmethyl)-4-piperidinyl]-2-propen-1-ol(750 mg, 2.16 mmol) from Example 1 in 30 ml of benzene was treated withmanganese dioxide (1.8 g, 20.7 mmol), and the resulting suspension washeated to reflux for 2 hours. The mixture was cooled to room temperatureand filtered through Celite®. The filtrate was concentrated to drynessto give 602 mg of a crude brown semi-solid.

¹ NMR (CDCl₃) δ 1.4-1.9 (m, 4H), 2.0 (dt, 2H), 2.15-2.3 (m, 1H), 2.4 (s,3H), 2.8-3.0 (m, 2H), 3.5 (s, 2H), 6.8 (s, 0.4H), 6.85 (s, 0.6H),7.0-7.18 (m, 1H), 7.2-7.9 (m, 9H) ppm.

The title compounds of Examples 6 and 7 were prepared by a methodanalogous to that described in Example 5.

EXAMPLE 62,5-Dimethyl-benzothien-2-yl-2-[1-(phenylmethyl)-4-piperidinyl]vinylketone

¹ H NMR (CDCl₃) δ 1.5-2.0 (m, 4H), 2.1 (dt, 2H), 2.2-2.4 (m, 1H), 2.56(s, 3H), 2.8 (s, 3H), 2.9-3.05 (m, 2H), 3.56 (s, 2H), 6.72 (s, 0.4H),6.8 (s, 0.6H), 7.06 (d, 0.6H), 7.1 (d, 0.4H), 7.3-7.8 (m, 8H) ppm.

EXAMPLE 7 Benzothien-2-yl-2-[1-(phenylmethyl)-4-piperidinyl]vinyl ketone

¹ H NMR (CDCl₃) δ 1.4-1.9 (m, 4H), 1.95-2.1 (dt, 2H), 2.2-2.35 (m, 1H),2.8-3.0 (m, 2H), 3.54 (s, 2H), 6.86 (s, 0.4H), 6.9 (s, 0.6H), 7.1 (d,0.6H), 7.15 (d, 0.4H), 7.2-8.0 (m, 10H) ppm.

EXAMPLE 81-(5-Methyl-benzo[b]thien-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone

A solution of crude 5-methyl-benzothien-2-yl2-[1-(phenylmethyl)-4-piperidinyl)]vinyl ketone from Example 5 (600 mg,1.6 mmol) in a mixture of ethanol (20 ml) and ethyl acetate (40 ml) wastreated with platinum oxide (PtO₂) (60 mg) and hydrogenated at 50 psifor 2 hours. (Thin layer chromatography indicated that the reaction wasnot complete). An additional 45 mg of PtO₂ was added and the mixture washydrogenated for an additional 1 hour. The mixture was filtered throughCelite® and the filtrate was concentrated to dryness and purifiedthrough chromatography using chloroform to 2% methanol in chloroform aseluent to give 232 mg of the title compound.

¹ H NMR (CDCl₃) δ 1.2-2.1 (m, 9H), 2.52 (s, 3H), 2.9-3.0 (m, 2H), 3.05(t, 2H), 3.52 (s, 2H), 7.2-7.4 (m, 6H), 7.7 (s, 1H)₁ 7.75 (d, 1H), 7.9(s, 1H) ppm.

The title compounds of Examples 9-11 were prepared by a method analogousto that described in Example 8.

EXAMPLE 91-(6-Methyl-benzo[b]thien-2-yl-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone

¹ H NMR (CDCl₃) δ 1.2-2.05 (m, 9H), 2.5 (s, 3H), 2.7-2.8 (m, 2H), 3.0(t, 2H), 3.5 (s, 2H), 7.2-7.4 (m, 6H), 7.65 (s, 1H), 7.8 (d, 1H), 7.9(s, 1H) ppm.

EXAMPLE 101-(3,5-Diethyl-benzo[b]thien-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone

¹ H NMR (CDCl₃) δ 1.2-2.0 (m, 9H), 2.5 (s, 3H), 2.75 (s, 3H), 2.8-3.0(m, 4H), 3.5 (s, 2H), 7.2-7.8 (m, 8H) ppm.

EXAMPLE 111-(Benzothien-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone

¹ H NMR (CDCl₃) δ 1.1-2.0 (m, 9H), 2.8-2.95 (m, 2H), 3.05 (t, 2H), 3.5(s, 2H), 7.2-7.5 (7H), 7.8-7.9 (m, 2H), 7.95 (s, 1H) ppm.

EXAMPLE 12 Benzofuran-2-yl-2-[1-(phenylmethyl)-4-piperidinyl]vinylketone

To a solution of diisopropylamine (0.5 ml, 3.6 mmol) in 15 ml of dry THFwas added 2.5 M n-butyllithium (1.3 ml, 3.3 mmol) at -78° C. Afterstirring at -78° C. for 20 minutes, a solution of benzofuran-2-yl methylketone (0.48 g, 3 mmol) in 3 ml of dry THF was added at -78° C. andstirred at that temperature for 1.5 hours. The mixture was quenched withwater and brine and extracted with ethyl acetate. The organic layer wasdried and concentrated to give 1.117 g of product as an oil. The oil wasdissolved in 15 ml of methylene chloride and treated with mesyl chloride(0.24 ml, 3 mmol) and triethylamine (0.42 ml, 3 mmol) at roomtemperature. The mixture was stirred at room temperature overnight, thenquenched with water and extracted with methylene chloride. The organiclayer was dried and concentrated to give 0.827 g of crude material whichwas purified through silica gel column chromatography using chloroformto 5% methanol in chloroform as eluent to give 430 mg of off-whitecrystals.

M.p. 186-188° C. ¹ H NMR (CDCl₃) δ 1.8-3.0 (m, 7H), 3.1-3.4 (m, 2H), 4.0(br s, 2H), 6.9 (s, 0.4H), 6.96 (s, 0.6H), 7.1 (d, 0.6H), 7.15 (d,0.4H), 7.2-7.7 (m, 1OH) ppm.

EXAMPLE 13Benzofuran-2-yl-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone

A solution of benzofuran-2-yl 2-[1-(phenylmethyl)-4-piperidinyl]vinylketone (410 mg) in a mixture of ethanol (70 ml) and ethyl acetate (40ml) was treated with platinum oxide (80 mg) and hydrogenated at 45 psifor 1 hour. The mixture was filtered through Celite® and the filtratewas concentrated to dryness to give an off-white solid which wasrecrystallized from ethyl acetate to give 162 mg of white crystals.

M.p. 199-200° C. ¹ H NMR (CDCl₃) δ 1.4-2.2 (m, 7H), 2.4-2.6 (m, 2H),2.97 (t, 2H), 3.3-3.5 (m, 2H), 4.1 (AB_(q), 2H), 7.1-7.7 (m, 10H) ppm.

EXAMPLE 141-[2-(N-Phenylsulfonyl-6-methyl-indolyl]-3-[1-(phenylmethyl)-4-piperidinyl]-2-propen-1-ol

A solution of N-phenylsulfonyl-6-methyl indole (1.18 g, 4.34 mmol) in 30ml of dry THF was cooled to -78° C. and treated with 3.5 ml (5.2 mmol)of 1.5 M lithium diisopropylamide in cyclohexane at -78° C. Afterstirring at -78° C. for 1 hour, a solution of3-[1-(phenylmethyl)-4-piperidinyl]-2-propenal (1.0 g, 4.36 mmol) in 5 mlof dry THF was added at -78° C. and stirred at that temperature for 40minutes. The mixture was quenched with water and extracted withchloroform. The organic layer was dried and concentrated to give 2.23 gof an orange oil. The oil was purified through silica gel columnchromatography using 2% methanol in chloroform as eluent to give 1.0 gof the title compound as a yellow oil.

¹ H NMR (CDCl₃) δ 1.4-1.8 (m, 4H), 1.9-2.1 (m, 3H), 2.45 (s, 3H),2.85-2.95 (m, 2H), 3.3 (br s, 1H), 3.5 (s, 2H), 5.6-5.9 (m, 3H), 6.55(s, 1H), 7.02 (dd, 1H), 7.2-7.9 (m, 12H) ppm.

EXAMPLE 15N-Phenylsulfonyl-6-methyl-indol-2-yl-2-[1-(phenyl-methyl)-4-piperidinyl]vinylketone

A solution of1-[2-(N-phenylsulfonyl-6-methyl-indolyl)]-3-[1-(phenylmethyl)-4-piperidinyl]-2-propen-1-ol(1.2 g, 2.4 mmol) in 30 ml of dry methylene chloride was treated withmanganese dioxide (MnO₂) (1.0 g, 11.5 mmol). The mixture was stirred for4 hours under reflux, cooled to room temperature and filtered throughCelite®. The filtrate was concentrated to give a yellow oil which waspurified through silica gel column chromatography using chloroform to2.5% methanol in chloroform as eluent to give 740 mg (62% yield) of thetitle compound as a yellow oil.

¹ H NMR (CDCl₃) δ 1.4-1.8 (m, 4H), 1.9-2.1 (m, 2H), 2.15-2.3 (m, 1H),2.5 (s, 3H), 2.85-3.0 (m, 2H), 3.5 (s, 2H), 6.55 (s, 0.45H), 6.65 (s,0.55H), 6.9 (d, 0.55H), 6.98 (d, 0.45H), 7.0 (s, 1H), 7.1 (d, 1H),7.25-7.55 (m, 9H), 7.9-8.1 (m, 3H) ppm.

EXAMPLE 161-(1-Phenylsulfonyl-6-methyl-indol-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone

A solution ofN-phenylsulfonyl-6-methyl-indol-2-yl-2-[1-(phenylmethyl)-4-piperidinyl]vinylketone (360 mg, 7.2 mmol) in a mixture of THF/ethanol (25 ml/25 ml) wastreated with platinum oxide (PtO₂) (40 mg) and hydrogenated at 45 psifor 75 minutes. The mixture was filtered through Celite®. The filtratewas concentrated to dryness to give a dark oil which was purified thoughsilica gel column chromatography using chloroform as eluent to give 200mg of the title compound as a yellow oil.

¹ H NMR (CDCl₃) δ 1.2-1.75 (m, 7H), 1.8-2.0 (m, 2H), 2.5 (s, 3H),2.8-3.0 (m, 4H), 3.5 (s, 2H), 7.0 (s, 1H), 7.1 (d, 1H), 7.2-8.0 (m, 12H)ppm.

EXAMPLE 171-(6-Methyl-indol-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone

A suspension ofN-phenylsulfonyl-6-methyl-indol-2-yl-2-[1-(phenylmethyl)-4-piperidinyl]ethylketone (150 mg) in 20 ml of methanol was treated with 1.5 ml of 2Nsodium hydroxide (NaOH), heated at reflux and stirred at thattemperature for 70 minutes. The mixture was quenched with water andextracted with chloroform. The organic layer was dried and concentratedto give 100 mg of the title compound as a brown solid.

¹ H NMR (CDCl₃) δ 1.2-1.8 (m, 7H), 1.8-2.0 (m, 2H), 2.42 (s, 3H),2.8-3.0 (m, 4H), 3.5 (s, 2H), 6.95 (d, 1H), 7.1 (s, 1H), 7.2-7.35 (m,6H), 7.55 (d, 1H) ppm.

EXAMPLE 181-(2-Benzothiazolyl)-3-[1-(phenylmethyl)-4-piperidinyl]-2-propen-1-ol

A solution of benzothiazole (0.243 g, 1.8 mmol) in 5 ml of dry THF wastreated with 1.5M lithium diisopropylamide in cyclohexane (1.45 ml) at-78° C. and stirred at that temperature for 15 minutes. A solution of3-[1-(phenylmethyl)-4-piperidinyl]propenal (452 mg, 1.97 mmol) in 3 mlof dry THF was added at -78° C. and stirred at that temperature for 30minutes. The mixture was quenched with water and extracted withchloroform. The organic layer was dried and concentrated to give a thickyellow oil in a quantitative yield.

¹ H NMR (CDCl₃) δ 1.6-2.15 (m, 7H), 2.85-3.0 (m, 2H), 3.5 (s, 2H), 5.5(d, 1H), 5.7-6.1 (m, 2H), 7.2-7.6 (m, 7H), 7.9 (d, 1H), 8.0 (d, 1H) ppm.

EXAMPLE 19 2-Benzothiazolyl-2-[1-(phenylmethyl)-4-piperidinyl]-vinylketone

A solution of1-(2-benzothiazolyl)-3-[1-(phenylmethyl)-4-piperidinyl]-2-propen-1-ol(654 mg, 1.8 mmol) in 25 ml of methylene chloride was treated with MnO₂(0.782 g, 9 mmol) and heated to reflux. After 3 hours, the mixture wasfiltered through Celite® and the filtrate was concentrated to give 0.655mg of a dark oil. The oil was purified through silica gel columnchromatography using 2% methanol in chloroform as eluent to give 0.487 gof an amber oil which was solidified upon standing overnight.

¹ H NMR (CDCl₃) δ 1.5-1.9 (m, 4H), 2.0-2.15 (m, 2H), 2.3-2.5 (m, 1H),3.5 (s, 2H), 7.2-7.6 (m, 9H), 8.0 (dd, 1H), 8.2 (dd, 1H) ppm.

EXAMPLE 201-(Benzothiazol-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone

A solution of 2-benzothiazolyl 2-[1-(phenylmethyl)-4-piperidinyl]vinylketone (146 mg, 0.4 mmol) in a mixture of ethyl acetate/ethanol (10ml/10 ml) was treated with PtO₂ (20 mg) and hydrogenated at 50 psi for 3hours. The mixture was filtered through Celite® and the filtrate wasconcentrated to dryness to give 0.154 g of a dark oil. The oil waspurified through silica gel column chromatography using chloroform aseluent to give 37 mg of the title compound as a brown oil.

¹ H NMR (CDCl₃) δ 1.2-1.4 (m, 3H), 1.7-1.85 (m, 4H), 1.85-2.1 (m, 2H),2.8-3.0 (m, 2H), 3.3 (dd, 2H), 3.5 (s, 2H), 7.2-7.4 (m, 5H), 7.45-7.65(m, 2H), 7.95 (dd, 1H), 8.2 (dd, 1H) ppm.

EXAMPLE 21 N-Phenylsulfonyl-5-nitroindole

A solution of 5-nitroindole (1.62 g, 10 mmol) in 30 ml ofdimethylformamide (DMF) was treated with 60% sodium hydride (0.44 g, 11mmol) at room temperature. After 3 minutes, benzenesulfonyl chloride(1.766 g, 10 mmol) was added. The mixture was stirred at roomtemperature overnight and treated with 250 ml of water. A precipitateformed and was filtered to give a yellow solid which was pumped in vacuoto give 2.7 g (89%) of the title compound.

¹ H NMR (CDCl₃) δ 6.82 (d, 1H), 7.45-7.55 (m, 2H), 7.6 (d, 1H), 7.72 (d,1H), 7.9 (m, 2H), 8.1 (d, 1H), 8.2 (dd, 1H), 8.5 (d, 1H) ppm.

EXAMPLE 22N-Phenylsulfonyl-5-nitroindol-2-yl-2-[1-(phenylmethyl)-4-piperidinyl]vinylketone

A solution of N-phenylsulfonyl-5-nitroindole (646 mg, 2.14 mmol) in 10ml of dry THF was treated with lithium diisopropylamide (1.5M incyclohexane) (1.7 ml, 2.6 mmol) at -78° C. After 1 hour at -78° C., asolution of 3-[4-(N-phenylmethylpiperidinyl] propenal (490 mg, 2.14mmol) in 2 ml of dry THF was added at -78° C. After 40 minutes at -78°C., the mixture was quenched with water and extracted with methylenechloride. The organic layer was dried and concentrated to give 1.149 gof a yellow oil. The oil was dissolved in 30 ml of benzene, treated withMnO₂ (1.86 g, 21.4 mmol) and heated at reflux for 4 hours. An additional900 mg of MnO₂ was added and the mixture was heated at reflux overnight.The mixture was filtered through Celite® and the filtrate wasconcentrated to give a brown oil which was purified through silica gelcolumn chromatography using chloroform as eluent to give the titlecompound as a brown oil.

¹ H NMR (CDCl₃) δ 1.45-1.95 (m, 4H), 1.95-2.1 (m, 2H), 2.15-2.4 (m, 1H),2.9-3.05 (m, 2H), 3.55 (s, 2H), 6.55 (s, 0.5H), 6.62 (s, 0.5H), 6.98 (d,0.5H), 7.05 (d, 1H), 7.1 (s, 1H), 7.2-7.4 (m, 4H), 7.5-7.7 (m, 4H),8.05-8.15 (m, 2H), 8.2-8.4 (m, 2H), 8.5 (d, 1H) ppm.

EXAMPLE 23N-Phenylsulfonyl-5-nitroindol-2-yl-2-[1-(phenylmethyl)-4-piperidinyl]ethylketone

A solution of N-phenylsulfonyl-5-nitroindol-2-yl2-[1-(phenylmethyl)-4-piperidinyl]vinyl ketone (187 mg, 0.35 mmol) in amixture of ethyl acetate/ethanol (20 ml/8 ml) was treated with PtO₂ (50mg) and hydrogenated at 40 psi for 1.5 hours. The mixture was filteredthrough Celite® and the filtrate was concentrated to give 177 mg (100%)of a brown oil.

¹ H NMR (CDCl₃) δ 1.1-2.0 (m, 9H), 2.75-2.9 (m, 2H), 2.92 (t, 2H), 3.42(s, 2H), 6.68 (d, 1H), 6.72 (dd, 1H), 6.8 (s, 1H), 7.1-7.5 (m, 8H),7.7-7.9 (m, 3H) ppm.

EXAMPLE 24 5-Nitroindol-2-yl 2-[1-(phenylmethyl)-4-piperidinyl]ethylketone

A solution of N-phenylsulfonyl-5-nitroindol-2-yl2-[1-(phenylmethyl)-4-piperidinyl]ethyl ketone (160 mg, 0.32 mmol) in 3ml of methanol and 2 ml of 2N NaOH was heated at reflux for 2 hours. Themixture was concentrated to dryness and the residue was diluted withbrine and extracted with chloroform. The organic layer was dried andconcentrated to dryness to give 144 mg of a brown solid which waspurified through silica gel column chromatography to give 31 mg of thetitle compound as a brown solid.

¹ H NMR (CDCl₃) δ 1.1-2.0 (m, 9H), 2.8-3.0 (m, 4H), 3.5 (s, 2H), 6.76(dd, 1H), 6.9 (s, 1H), 6.96 (s, 1H), 7.1-7.3 (m, 6H) ppm.

EXAMPLE 251-(1-Ethyl-2-methyl-1H-benzimidazol-5-yl)-3-[(1-phenylmethyl)-4-piperidinyl]-2-propen-1-one

A mixture of 0.1 g (0.5 mM) of 1-ethyl-2-methylbenzimidazole-5-yl methylketone and 0.1 g (0.5 mM) 4-formyl-N-benzylpiperidine in 10 mL oftetrahydrofuran (THF) was cooled to -78° C. under a nitrogen atmosphere.To this mixture were added dropwise 0.5 mL (0.5 mM) of a IM solution oflithium bis(trimethylsilyl)amide in THF. The reaction was stirred at-78° C. for 1 hour, then warmed to room temperature. To the reaction wasadded 10 mL of water and the pH was adjusted to 2.0 with 1N hydrochloricacid (HCl). The mixture was extracted with 15 mL of ethyl acetate. ThepH of the water layer was then sequentially adjusted to 3.0, 4.0, 5.0,6.5, and 8.5 with IN NaOH, each time extracting with 15 mL of ethylacetate. The ethyl acetate extracts at pH=5.0 and 6.5 were combined,dried with sodium sulfate (Na₂ SO₄) and evaporated to yield 50 mg (26%)of the title compound as an oil.

Thin layer chromatography (TLC) (10:1 CHCl₃ :CH₃ OH), R_(f) =0.58.

¹ H NMR (CDCl₃) δ 8.22 (s, 1H), 7.88 (d, 1H), 7.30 (m, 5H), 6.90 (m,3H), 4.14 (q, 2H), 3.50 (s, 2H), 3.05 (m, 2H), 2.85 (m, 2H), 2.61 (s,3H), 1.4-2.1 (m, 5H), 1.40 (t, 3H).

EXAMPLE 261-(1-Ethyl-2-methyl-1H-benzimidazol-5-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanonehydrochloride

To a solution of the title compound from Example 25 0.14 g (0.36 mM) in20 mL of ethanol were added 10 mg of PtO₂ and the mixture washydrogenated at 50 psi for 1 hour. The reaction was filtered and theethanol solvent evaporated. The residue was suspended in 50 mL of a 1:1mixture of ethyl acetate: H₂ O, and the pH adjusted to 8.5 with 1Nsodium hydroxide (NaOH). The ethyl acetate layer was dried (Na₂ SO₄) andevaporated to yield 0.1 g (72%) of the free base of the title compoundas an oil.

TLC (10: 1 CHCl₃ :CH₃ OH), R_(f) =0.64.

¹ H NMR (CDCl₃) δ 8.26 (s, 1H), 7.92 (d, 1H), 7.28 (m, 6H), 4.18 (q,2H), 3.48 (s, 2H), 3.05 (m, 2H), 2.85 (m, 2H), 2.54 (s, 3H), 1.4-2.0 (m,9H), 1.30 (t, 3H).

The oil was dissolved in ethyl acetate and to this solution was addeddropwise a solution of HCl dissolved in ether. The resulting precipitatewas filtered and triturated with hexanes to yield 0.105 g of the titlecompound as a hygroscopic white solid.

M.p.=165-167° C. Mass spectrum: 389.2 (p), 298.0 (p-91), 172.0 (p-217),90.9 (p-298, base peak).

EXAMPLE 271-(2-Methyl-6-benzothiazolyl)-3-[1-(phenylmethyl)-4-piperidinyl]-2-propen-1-one

A mixture of 0.191 g (0.001 M) of 2-methyl-6-benzothiazolyl methylketone (prepared as described by S. S. Sawhney, J. Singh, and O. P.Bansal, J. Ind. Chem. Soc., 12, 561 (1975)) and 0.203 g (0.001 M) of4-formyl-N-benzyl piperidine in 5 mL of THF was cooled to -78° C. undera nitrogen atmosphere. To this solution were added dropwise 0.73 mL(0.0011 M) of lithium diisopropylamide (1.5 M solution in THF). Thereaction was stirred at -78° C. for 1 hour and then warmed to 0° C. Thereaction was quenched with 5 mL of water and extracted with ethylacetate. The ethyl acetate extracts were dried (Na₂ SO₄) and evaporatedto yield 0.4 g of a brown gum. This residue was chromatographed on 30 gof silica gel using a 98:2 mixture of CH₂ Cl₂ :CH₃ OH as the eluant.Appropriate fractions were combined to yield 0.122 g (32%) of the titlecompound as an amorphous solid. TLC (10:1 CH₂ Cl₂ :CH₃ OH) R_(f) =0.63.

¹ H NMR (CDCl₃) δ 8.42 (s, 1H), 7.9 (m, 2H), 7.35-7.5 (m, 5H), 6.8-7.1(m, 2H), 3.52 (s, 2H), 2.95 (m, 2H), 2.8 (s, 3H), 1.4-2.5 (m, 7H). Massspectrum: 376.1600. Calc'd for C₂₃ H₂₄ N₂ OS: ±2.6 ppm.

EXAMPLE 281-(2-Methyl-6-benzothiazolyl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanonehydrochloride

A solution of 0.120 g (0.319 mM) of the free base of the title compoundfrom Example 27 was dissolved in 50 mL of ethanol. To this was added 50mg of Pt2O and the mixture hydrogenated at 50 psi for 1 hour. Thereaction was filtered and the ethanol was evaporated to yield 0.112 g(100%) of the title compound (free base) as an amorphous solid.

TLC (10:1 CH₂ Cl₂ :CH₃ OH) R_(f) =0.5.

¹ H NMR (CDCl₃) δ 8.45 (s, 1H), 8.02 (dd, 2H), 7.25 (m, 5H), 3.5 (s,2H), 3.02 (m, 2H), 2.85 (m, 2H), 2.83 (s, 3H), 1.4-2.0 (m, 9H). Massspectrum: 378 (p), 287 (p-91), 172 (p-206), 91 (p-287, base peak).

This residue was dissolved in 15 mL of ethyl acetate to which was addedHCl dissolved in ethyl acetate (EtOAc). The resulting precipitate wasfiltered and dried under vacuum to yield 92 mg (70%) of the titlecompound.

M.p.=110°-112° C.

EXAMPLE 29 N-Acetyl-4-aminoacetophenone

A mixture of 5.0 g (0.37 M) of 4-aminoacetophenone, 3.8 mL (0.04 M) ofacetic anhydride, and 5.5 mL (0.04 M) of triethylamine were dissolved in50 mL of methylene chloride (CH₂ Cl₂) and stirred at room temperaturefor 18 hours. A white solid precipitated from the solution and wascollected by filtration. The solid was washed with water and air driedto yield 3.32 g (49%) of N-acetyl-4-aminoacetophenone.

TLC (1:1 CHCl₃ :EtOAc) R_(f) =0.61.

¹ H NMR (CDCl₃) δ 8.58 (br s, 1H), 7.90 (d, 2H), 7.64 (d, 2H), 2.56 (s,3H), 2.19 (s, 3H).

EXAMPLE 30 N-Benzoyl-4-aminoacetophenone

A mixture of 5.0 g (0.37 M) of 4-aminoacetophenone, 4.7 mL (0.04 M) ofbenzoyl chloride, and 5.5 mL (0.04 M) of triethylamine were dissolved in50 mL of methylene chloride (CH₂ Cl₂) and stirred at room temperaturefor 18 hours. The resulting precipitate was filtered and washed withwater. The residue was dissolved in chloroform (CHCl₃) and dried withNa₂ SO₄. Evaporation of the CHCl₃ yielded 4.2 g (47%) ofN-benzoyl-4-aminoacetophenone.

M.p.=206°-208° C. ¹ H NHR (CDCl₃ +DMSO) δ 9.58 (br s, 1H), 7.80 (m, 6H),7.34 (m, 3H), 2.44 (s, 3H).

EXAMPLE 31 N-Acetyl-3-nitro-4-aminoacetophenone

To 10 mL of fuming nitric acid cooled to 0° C. was added portionwise 1.0g (5.6 mM) of N-acetyl-4-aminoacetophenone. The temperature wasmaintained below 5° C. to prevent excess nitration of the benzene ring.The solution was stirred for 15 minutes at 0° C. and then carefullypoured onto ice. A yellow solid precipitated and was collected byfiltration to yield 0.42 g (34%) of the title compound.

TLC (2:1 CHCl₃ :EtOAc) R_(f) =0.78.

¹ H NMR (CDCl₃) δ 8.9 (d, 1H), 8.77 (s, 1H), 8.16 (s, 1H), 2.64 (s, 3H),2.34 (s, 3H).

EXAMPLE 32 N-Benzoyl-3-nitro-4-aminoacetophenone

To 10 mL of fuming nitric acid cooled to -5° C. were added portionwise2.5 g (0.01 M) of N-benzoyl-4-aminoacetophenone. The temperature wasmaintained below 0° C. The reaction was stirred for 10 minutes and theresulting solution poured onto ice. A yellow solid precipitate wasformed which was collected by filtration. The solid was dissolved inCHC1₃ and chromatographed on silica gel using CHCl₃ as the elutant.Appropriate fractions were combined and evaporated to yield 1.0 g (35%)of the title compound as a yellow solid.

¹ H NMR (CDCl₃) δ 9.12 (d, 1H), 8.84 (s, 1H), 8.25 (d, 1H), 7.96 (d,2H), 7.6 (m, 3H), 2.66 (s, 3H).

EXAMPLE 333-[1-(1-Phenylmethyl)-4-piperidinyl]-1-(3-nitro-4-acetamido-phenyl)2-propen-1-one

A solution of 2.6 g (11.7 mM) of N-acetyl-3-nitro-4-aminoacetophenone in25 mL of THF was cooled to -60° C. under a nitrogen atmosphere. To thesolution were added 4.7 mL (11.7 mM) of N-butyllithium (2.5 M inhexanes), maintaining the temperature below -60° C. The reaction wasstirred for 15 minutes. A solution of 4-formyl-N-benzylpiperidinedissolved in 5 mL of THF was added dropwise, maintaining the reactiontemperature below -55° C. The reaction was stirred for 1 hour and thenwarmed to room temperature. At room temperature, the reaction wasquenched with 10 mL of water and extracted with ethyl acetate. The ethylacetate extracts were combined, dried (Na₂ SO₄) and evaporated to yielda dark oil. This oil was chromatographed on silica gel using 5:1 CHCl₃:EtOAc as the elutant. Appropriate fractions were combined to yield 1.2g (25%) of the title compound as an oil which slowly crystallized.

TLC (10:1 CHCl₃ :CH₃ OH), R_(f) =0.45.

¹ H NMR (CDCl₃) δ 8.90 (d, 1H), 8.76 (s, 1H), 8.14 (d, 1H), 8.30 (m,5H), 3.53 (s, 2H), 2.94 (m, 2H), 2.32 (s, 3H), 1.5-2.15 (m, 5H).

EXAMPLE 343-[1-(Phenylmethyl)-4-piperidinyl]-1-(3-nitro-4-benzoyl-amidophenyl)2-propen-1-one

A solution of 0.80 g (2.90 mM) of the title compound from Example 32 in30 mL of anhydrous THF was cooled to -70° C. under a nitrogenatmosphere. To the solution were added 1.2 mL (2.9 mM) of N-butyllithium(2.5 M solution in hexanes) dropwise, forming a dark solution. Thesolution was stirred at -70° for 10 minutes. To this mixture was addeddropwise a solution of 0.6 g (2.9 mM) of 4-formyl-N-benzylpiperidine in10 mL of THF. The reaction was slowly warmed to room temperature andstirred for 18 hours. The reaction mixture was quenched with 25 mL ofwater and extracted with ethyl acetate. The ethyl acetate extracts weredried (Na₂ SO₄) and evaporated. The residue was chromatographed onsilica gel using 1:1 CHCl₃ :EtOAc as the eluent. Appropriate fractionswere combined to yield 0.45 g (34%) of the title compound as anamorphous solid.

TLC (10:1 CHCl₃ :CH₃ OH), R_(f) =0.67.

¹ H NMR (CDCl₃) δ 9.14 (d, 1H), 8.82 (s, 1H), 8.22 (d, 1H), 7.98 (d,2H), 7.55 (m, 3H), 7.32 (m, 5H), 7.10 (m, 1H), 6.85 (m, 1H), 3.54 (s,1H), 2.95 (m, 2H), 1.4-2.3 (m, 7H).

EXAMPLE 351-(3-Amino-4-acetamidophenyl)-3-[(1-phenylmethyl)-4-piperidinyl]-1-propanone

To a solution of 0.9 g (2.2 mM) of the title compound from Example 33 in50 mL of ethanol were added 20 mg of PtO₂, and the mixture washydrogenated at 50 psi for one hour. The mixture was filtered and theethanol evaporated to yield 0.9 g (100%) of the title compound as anoil.

¹ H NMR (CDCl₃) δ 7.6 (8, 1H), 7.2-7.5 (m, 7H), 3.5 (8, 2H), 2.85 (m,4H), 2.21 (s, 3H), 1.2-2.0 (m, 9H). Mass spectrum: 379.2 (p), 202.3(p-176.9), 172.3 (p-206.9), 91.0 (p-288.3, base peak).

EXAMPLE 361-(2-Methyl-1H-benzimidazol-5-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanolhydrochloride

A solution of 0.6 g (1.6 mM) of the free base of the title compound fromExample 35 in 10 mL of acetic acid was heated on a steam bath (80°-90°C.) for 1 hour. The acetic acid was evaporated and the residue dissolvedin 25 mL of ethyl acetate. To this was added 25 mL of water and the pHwas adjusted to 3.0. The ethyl acetate layer was separated from thewater layer and the water layer was sequentially adjusted to pH=5.0,6.0, and 9.0, each time extracting with ethyl acetate. The pH=9.0 ethylacetate extract was dried (Na₂ SO₄) and evaporated to afford 0.4 g (69%)of the free base of the title compound (free base).

¹ H NMR (CDCl₃) δ 8.08 (s, 1H), 7.80 (s, 1H), 7.47 (m, 1H), 7.25 (m,6H), 3.47 (s, 2H), 2.8-3.0 (m, 4H), 2.59 (s, 3H), 1.90 (t, 2H), 1.64 (m,4H), 1.25 (m, 3H).

TLC (10:1:0.1 CHCl₃ :CH₃ OH: NH₄ OH), R_(f) (free base)=0.50.

The amorphous solid was dissolved in ethyl acetate and to this was addedan ether solution of hydrogen chloride (HCl). The resulting precipitatewas filtered and dried to yield 0.26 g (62%) of the title compound as atan solid.

Mass spectrum: 361.3 (p), 270.2 (p-91.1), 172.3 (p-189), 91.1 (0-270.2,base peak).

EXAMPLE 371-(3-Amino-4-benzoylamidophenyl)-3-[1-phenylmethyl)-4-piperidinyl]-1-propanone

To a solution of 0.45 g (1.0 mM) of the title compound from Example 34in 50 mL of ethanol were added 25 mg of PtO₂ and the mixture washydrogenated at 50 psi for 1 hour. After filtration to remove thecatalyst, the ethanol was evaporated to yield the title compound as anamorphous solid.

¹ H NMR (CDCl₃) δ 8.15 (8, 1H), 7.90 (d, 2H), 7.2-7.7 (m, 10H), 3.88 (brs, 2H), 3.50 (s, 2H), 2.90 (m, 4H), 1.2-2.0 (m, 9H).

This material was used in the procedure of Example 38 without furtherpurification.

EXAMPLE 381-(2-Phenyl-1H-benzimidazol-5-yl)-3-[(1-phenylmethyl)-4-piperidinyl]-1-propanonehydrochloride

The title compound of Example 37 was dissolved in a 50:50 mixture ofethanol and acetic acid and heated to 75° C. for 3 hours. The reactionwas cooled to room temperature and diluted with water. The pH of themixture was adjusted to 9.5 and the mixture was extracted with ethylacetate. The ethyl acetate extracts were dried (Na₂ SO₄) and evaporatedto yield 0.19 g (45%) of the free base of the title compound.

TLC (10:1:0.1 CHCl₃ :CH₃ OH:NH₄ OH), R_(f) =0.40.

¹ H NMR (CDCl₃) δ 8.14 (d, 2H), 7.86 (d, lH), 7.2-7.6 (m, 11H), 3.58 (s,2H), 2.92 (m, 4H), 1.2-2.1 (m, 9H).

The residue was dissolved in ethyl acetate, and to this solution wasadded dropwise an ether solution of HCl. The resulting precipitate wascollected via filtration and dried to yield the title compound as a tansolid.

M.p.>300° C. Mass spectrum: 424.2 (p+1).

EXAMPLE 39 1-(2-Methyl-6-benzthiazolyl)-3-(4-piperidinyl)-1-propanone

A mixture of 0.90 g (2.38 mM) of1-(2-methyl-6-benzthiazolyl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone(Example 27) and 0.33 mL (3.1 mM) of 1-chloroethyl chloroformate wasrefluxed in 10 mL of 1,2-dichloroethane for 2 hours. The resulting brownsolution was cooled to room temperature and diluted with 15 mL of water.This mixture was extracted twice with 20 mL of ethyl acetate. The ethylacetate extracts were combined, dried (Na₂ SO₄), and evaporated to yield1.0 g (100%)1-(2-methyl-6-benzothiazolyl)-3-[(1-chloroethylformyl)-4-piperidinyl]-1-propanoneas an oil.

TLC (10:1 CH₂ Cl₂ :CH₃ OH) R_(f) =0.86.

¹ H NMR (CDCl₃) δ 8.4 (s, 1H), 7.9 (m, 2H), 6.55 (q, 1H), 2.65-3.2 (m,4H), 2.77 (s, 3H), 1.83 (d, 3H), 1.4-1.95 (m, 9H). ¹³ C NMR (CDCl₃, ppm)198.1, 171.3, 155.8, 137.4, 135.8, 133.4, 125.9, 122.1, 122.0, 83.3,44.2 (2), 35.7, 35.3, 32.0, 30.4 (2), 25.4, 20.3.

A methanol solution (5 mL) of 0.9 g (2.28 mM) of the above oil wasrefluxed for 1 hour. Upon cooling, a yellow precipitate formed. Thisprecipitate was dissolved in 4N HCl and the solution extracted withether. The HCl solution was adjusted to pH 9 with sodium carbonate (Na₂CO₃) and extracted with ethyl acetate. The ethyl acetate extracts weredried (Na₂ SO₄), and evaporated to yield 0.250 g (38%) of the titlecompound as an amorphous yellow solid.

TLC (10:1 CH₂ Cl₂ :CH₃ OH) R_(f) =0.01.

¹ H NMR (CDCl₃) δ 8.5 (s, 1H), 7.95 (m, 2H), 32 (m, 2H), 2.85 (s, 1H),2.6 (m, 2H), 1.1-1.8 (m, 9H). ¹³ C NMR (CDCl₃, ppm) 198.1, 156.3, 136.0(2), 132.0, 125.9, 122.3, 122.1, 46.4 (2), 35.8, 35.7, 33.0, 31.4 (2),20.5.

EXAMPLE 401-(2-Methyl-6-benzothiazolyl)-3-[1-(2-methyl-4-thiazolyl)methyl]-4-piperidinyl]-1-propanonehydrochloride

A mixture of 250 mg (0.87 mM) of the title compound of Example 39, 0.160mg (0.87 mM) of 2-methyl-4-chloromethyl thiazole and 0.36 mL (2.60 mM)of triethylamine was refluxed in 5 mL methylene chloride for 12 hours.The reaction was cooled to room temperature and diluted with 10 mL ofwater. The mixture was extracted with ethyl acetate, and the ethylacetate extracts combined, dried (Na₂ SO₄), and evaporated to yield 0.27g of a yellow gum. This material was chromatographed on 10 g of silicagel using 98:2 CHCl₃ :CH₃ OH as an elutant. Appropriate fractions werecombined and evaporated to yield 100 mg (29%) of the title compound as ayellow amorphous solid.

TLC (10:1 CH₂ Cl₂ :CH₃ OH), R_(f) =0.21.

¹ H NMR (CDCl₃) δ 8.50 (s, 1H), 7.9 (m, 2H), 6.87 (s, 1H), 3.62 (5, 2H),3.0 (m, 4H), 2.87 (s, 3H), 2.69 (s, 3H), 2.0 (t, 2H), 1.7 (m, 4H), 1.35(m, 3H). Mass Spectrum: 399.2 (p), 287.2 (p-112, base peak), 223.1(p-176.1), 193.1 (p-206.1), 176.0 (p-223), 112.0 (p-287), 71.0 (p-328).

This material was dissolved in ethyl acetate and to it was added anether solution of HCl gas. The resulting precipitate was filtered andrecrystallized from CH₂ Cl₂ /ether to yield 92 mg of the title compound.

M.p.=184°-186° C.

EXAMPLE 411-(5-Amino-indol-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone

A solution of1-(1-Phenylsulfonyl-5-amino-indol-2-yl)-3-(N-phenylmethylpiperidin-4-yl)-1-propanone(160 mg, 0.32 mmol) in 3 ml of methanol and 2 ml of 2N NaOH was heatedat reflux for 2 hours. The mixture was concentrated to dryness and theresidue was diluted with brine and extracted with chloroform. Theorganic layer was dried and concentrated to dryness to give 144 mg ofbrown solid which was purified through silica gel column chromatographyto give 31 mg of the title compound as a brown solid.

¹ H NMR (CDCl₃) δ 1.1-2.0 (m, 9H), 2.8-3.0 (m, 4H), 3.5 (s, 2H), 6.76(dd, 1H), 6.9 (s, 1H), 6.96 (s, 1H), 7.1-7.3 (m, 6H)ppm.

EXAMPLE 42 1-(5-N-acetylamino-indol-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone

A solution of1-(5-amino-indol-2-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanone(18 mg, 0.05 mmol) in 0.5 ml of methylene chloride was treated with asolution of triethylamine (6 mg, 0.06 mmol) in 0.5 ml of methylenechloride and a solution of acetyl chloride (4.7 mg, 0.06 mmol) in 0.5 mlof methylene chloride at room temperature and the mixture was stirred atroom temperature for 4 hours. The mixture was quenched with water andextracted with methylene chloride. The organic layer was dried andconcentrated to give 11 mg of the title compound.

¹ H NMR (CDCl₃) δ 1.2-2.1 (m, 9H), 2.2 (s, 3H), 2.8-3.0 (m, 4H), 3.5 (s,2H), 7.0-7.65 (m, 9H), 8.0 (s, 1H), 9.35 (s, 1H) ppm.

We claim:
 1. A compound of the formula ##STR14## wherein the side chaincontaining --C(═Z)-- may optionally be attached to the carbon atomdesignated by an asterisk in ring B rather than to a member of ring Aand R² or R³ may optionally be attached to ring B rather than ringA;ring A is benzo; R¹ is phenyl, phenyl-(C₁ -C₆) alkyl, cinnamyl orheteroarylmethyl, wherein the heteroaryl moiety of said heteroarylmethylis selected from imidazolo, thiazolo, thieno, pyrido and isoxazolo, andwherein said phenyl and said heteroaryl moiety may optionally besubstituted with one or two substituents independently selected from (C₁-C₆) alkyl, (C₁ -C₆)alkoxy and halo; R² and R³ are independentlyselected from hydrogen, (C₁ -C₆)alkoxy, (C₁ -C₆) alkyl optionallysubstituted with from one to three fluorine atoms, benzyloxy, hydroxy,phenyl, benzyl, halo, nitro, COOR⁴, CONHR⁴, NR⁴ R⁵, NR⁴ COR⁵, or SO_(p)CH₂ -phenyl wherein p is 0, 1 or 2; R⁴ and R⁵ are independently selectedfrom hydrogen and (C₁ -C₆) alkyl, or R⁴ and R⁵, when part of said NR⁴R⁵, optionally form, together with the nitrogen to which they areattached, a ring containing four to eight members wherein one atom ofthe ring is nitrogen and the others are carbon, oxygen or nitrogen, orR⁴ and R⁵, when part of said NR⁴ COR⁵, optionally form, together withthe nitrogen and carbon to which they are attached, a four to eightmembered lactam ring; X is nitrogen; Y is oxygen, or NR⁶ R⁶ is hydrogen,(C₁ -C₆)alkyl, or CO(C₁ -C₆)alkyl; n is an integer from 1 to 4; each qis independently 1 or 2; and Z is oxygen or sulfur; with the provisothat any CH_(q) group wherein q is 1 must be attached to one and onlyone other CH_(q) group wherein q is 1; or a pharmaceutically acceptablesalt of such compound.
 2. A compound according to claim 1, having theformula ##STR15## wherein X is N; Y is NH, NCH₃, NCH₂ CH, or O; R² andR¹ are independently selected from the group consisting of (C₁-C₄)alkyl, chloro, fluoro, methoxy, amino and --NHC(═O)CH₃ ; and R¹ isbenzyl, methoxybenzyl, fluorobenzyl or a group of the formula ##STR16##wherein W is hydrogen, (C₁ -C₆)alkyl, phenyl or benzyl.
 3. A compoundaccording to claim 2, wherein X is N; Y is NH or NCH₃ ; and R² and R³are independently selected from the group consisting of (C₁ -C₄)alkyl,chloro, fluoro, methoxy, amino and --NHC(═O)CH₃ and R¹ benzyl.
 4. Acompound according to claim 3, wherein R² and R³ are independentlyselected from the group.
 5. A compound according to claim 1, selectedfrom the group consistingof:1-(2-methyl-1H-benzimidazol-5-yl)-3-[(1-(phenylmethyl)-4-piperidinyl]-1-propanonehydrochloride;1-(2-phenyl-1H-benzimidazol-5-yl)-3-[1-(phenylmethyl)-4-piperidinyl]-1-propanonehydrochloride; and1-(1-ethyl-2-methyl-1H-benzimidazol-5-yl)-3-[1-(phenylmethyl)-4-piperidinyl)-1-propanonehydrochloride.
 6. A pharmaceutical composition for enhancing memory ortreating or preventing Alzheimer's disease comprising a compoundaccording to claim 1 and a pharmaceutically acceptable carrier.
 7. Apharmaceutical composition for inhibiting cholinesterase in a mammal,comprising a compound according to claim 1 and a pharmaceuticallyacceptable carrier.
 8. A method of inhibiting cholinesterase in amammal, comprising administering to a mammal a cholinesterase inhibitingamount of a compound according to claim
 1. 9. A method of enhancingmemory or treating or preventing Alzheimer's disease, comprisingadministering to a patient a memory enhancing effective amount of acompound according to claim 1.